The ans is :- B) mv3 / (4g√2)
When the particle is at top the velocity is v cos 45 since the velocity is only having an x-component and not a y-component
V= vcos45
The time required to reach the top is vsin45/g
There The height = r = vsin45 * vsin45/g - 1/2* g*v2sin245/g2
On solving
r = v2sin245/2g
The angular momentum is mvr
m*vcos45*v2sin245/2g
m*v(1/√2)*v2(1/√2)2/(2g)
Therefore
The angular momentum is mv3/(4g√2)