The Isotopes of Promethium, and Are Unstable, and Lie

Multiple Choice

The isotopes of promethium, and are unstable, and lie on opposite sides of the "line of stability". Which of the following combinations is most likely to represent the type of decay for these isotopes?

A) Promethium-144, β decay; Promethium-134, positron decay
B) Promethium-144, positron decay; Promethium-134, β decay
C) Promethium-144, positron decay; Promethium-134, electron capture
D) Promethium-144, electron capture; Promethium-134, positron decay
E) Promethium-144, β decay; Promethium-134, γ decay