Two point charges a and b whose magnitudes are same positioned at a certain distance along the positive x-axis from each other . a is at origin and b is at a distance $\;x_{0}\;$ from a . Graph is drawn between electrical field strength and distance x from a . E is taken positive if it is along the line joining from a to b . Then

Question

$(a)\;a\;is\;+ve,b\;is\;-ve\qquad(b)\;a\;and\;b\;both\;are\;+ve\qquad(c)\;both\;are\;-ve\qquad(d)\;a\;is\;-ve\;,b\;is\;+ve$