True about congenital diseases in diabetes mellitus is all except:
Results due to free radical injury
6-10% cases are associated with major congenital abnormality
1-2% of newborns are associated with single umbilical artery
Insulin can be given
Lets see each option separately -
Congenital disease in diabetes mellitus
Option a i.e. Results due to free radical injury - True -
Congenital malformation in a case of diabetes can be due to variety of reasons like, Dutta Obs. 6/e, p 287

Genetic susceptibility
Hyperglycemia - It is seen that good glycemic control indicated by HbAIC levels < %.9 can significantly lower the risk of fetal malformation.
Arachidonic acid deficiency
Ketone body formation
Free Radical injury
Somatomedin inhibition.

Option b–6 to 10% cases are associated with major congenital abnormality
Here we will have to read the option very carefully - the option is talking about Major congenital anomalities and not all anomalies.
Dutta Obs 6/e, p- 287 says overall incidence of congenital Malformations is 6-10%.
Williams 24/e p 1128. “The incidence of major malformations in women with type I diabetes is ~ 5%”
Hence option b is incorrect
Option c - 1 - 2% of newborns are associated with single umbilical artery
This option can be taken in + /– status because no where the incidence of single umbilical artery in a case of diabetes has been mentioned separately.
Whatever little information we have is from Dutta Obs. 6/e, p 220
Single umbilical artery:

It is present in 1-2% cases (overall)
May be due to failure of development of artery or due to its atrophy in later months
It is seen in case of

i. Twins
ii. Babies born to diabetic mothers
iii. In polyhydramines

Single umbilical artery has been associated with congenital malformations of the fetus in 10-20% cases viz- Renal & Genital anomalies and fetal Trisomy
There is increased incidence of abortions, prematurity, IUGR and increased perinatal mortality.

Option d- insulin can be given
There is no doubt as far as this option is concerned as insulin is the TOC for controlling hyperglycemia in case of diabetes in pregnancy.
So from above discussion it is clear that option ‘b’ is absolutely incorrect, so we are opting it out.