Identify the direct object

The baseball pitcher threw his teammate on first base the ball

A. Pitcher

B. Teammate

C. First base

D. Ball

The direct object is the ball.

The baseball pitcher threw his teammate on first base a ball.

first we find the subject ... it is pitcher

now we find the verb ... it is threw

to find the direct object, find the verb and ask " what " ...

so the pitcher threw what?

he threw a ball ... so the direct object is ball.