Why does the president pro tempore usually preside over the senate?

a. the u. s. constitution provides for the leadership of the senate
b. the vice president is not allowed in the senate chambers during debates or discussions
c. the vice president usually devotes time to executive branch duties
d. the president pro tempore is the majority leader in the senate

what role does congress play in checking the power of the executive branch? a. reviews acts of congress for compliance with the constitution
b. the president may veto legislation
c. overrides presidential vetoes
d. creates lower courts and may remove judges through impeachment