Two particles a and b are performing shm along same straight line with same amplitude a and same angular frequency o . att = 0, a is at the left extreme and b is at a distance a/2 from mean position to the right of mean position and moving toward mean position. then:

a. their phase difference is 5π3
b. their phase difference is 2π3
c. time after which they cross each other is 2π3o
d. time after which they cross each other is π3o