Which of the following electron configurations is impossible?
Group of answer choices
a. 1s²2s²2p⁶3s²3p¹
b. 1s²2s²2p⁶3s²3p³
c. 1s²2s²2p⁸3s²3p⁵
d. 1s²2s²2p⁶3s²3p⁶
e. 1s²2s²2p⁶3s²3p³